Objective To determine associations between weight gain induced by antipsychotic and the polymorphisms of HTR2C gene -759C/T and -697G/C,histamine-1 receptor gene,leptine gene -2548G/A,and adiponectin gene +276G/T and +45T/G.Methods In the casematched study,85 patients who gained more than 7％ of their pre-drug body weight served as the study group and another 85 patients who gained less than 7％ of their pre-drug body weight served as the control group.The ligation diction reaction technique was used to analyze the frequencies of the -759C/T and -697G/C polymorphism of the HTR2C gene,-2548A/G polymorphism of leptin gene,+ 276G/T and + 45T/G polymorphism of adiponectin gene and glu349asp polymorphism of H1 receptor gene.Results The presence of the -759C allele,-697G allele,-2548A allele and + 276G allele was significantly higher in the study group than that in the control group (P ＜ 0.05 ).Conclusion The -759C/T and -697G/C polymorphisms of the promoter region of 5HT2C receptor gene,-2548A/G polymorphisms of leptin gene and + 276G/T polymorphisms of adiponectin gene may be associated with the antipsychotic induced weight gain.The glu349asp polymorphisms of histamine-1 receptor gene is not associated with antipsychotic induced weight gain.